Mount Vernon, IA Weather

Key Messages

- Above normal temperatures and mostly dry conditions are forecast into early next week with slightly cooler temperatures and isolated showers possible towards the middle to end of next week.

Short Term

Issued at 1234 AM CDT Sat Oct 24 2026

Comfortable, above average temperatures are expected today with highs in the mid-70s as an upper-level ridge sits over the Mississippi River Valley. A weak cold front will move into northwestern Iowa and Minnesota, tightening the pressure gradient across the region. Southerly wind gusts up to 20 mph are possible (40-60% chance) late this morning into the afternoon hours north of I-80 in eastern Iowa.

The front is forecasted to reach eastern Iowa tonight. Dry low- to-mid-levels should prohibit precipitation development. Despite this, lingering clouds will cut into the radiational cooling with lows only dropping into the low-to-mid-50s. Heading into Sunday, the weak boundary stalls out with no dynamical support aloft, and without an air mass change, highs will once again climb in the mid-to-upper 70s.

Long Term

Issued at 1234 AM CDT Sat Oct 24 2026

Sunday Night-Tuesday...A shortwave trough over the Desert Southwest ejects to the northeast into the Northern Plains. A Front Range low across eastern Colorado is expected to deepen and track across the Central Plains into Minnesota Monday into Tuesday. This passage will wash out the weak front draped across Iowa and northern Illinois as winds shift from easterly back to southerly. Mid-level moisture advection could be sufficient enough to support isolated rain showers (10-20% chance) Monday night into Tuesday.

Tuesday Night-Wednesday...Another shortwave trough swings into the Northern Plains Tuesday night. Surface cyclogenesis will occur quickly in the wake of the previous low pressure, but the fast propagation speed of the trough is expected to limit significant pressure falls. By Wednesday evening, the new low pressure moves across Minnesota into southern Canada, dragging a cold front southeastward into eastern Iowa and northern Illinois. PoPs on Wednesday again will be isolated (10-30%) due to the lack of low-level moisture return.

Thursday-Friday...In wake of Wednesday's cold front, westerly flow could advect in some cooler air with highs falling back in the 60s and low 70s, still above average for the end of October. This will not last long though as high pressure over the Ohio River Valley shifts our winds back out of the south Thursday night, keeping small PoPs (20-40%) around late week.

Aviation

Issued at 609 AM CDT Sat Oct 24 2026

Similar weather conditions to yesterday will be seen today, with passing high clouds and very good visibility seen through the period. Winds today will be south to southeast around 7 to 10 kts, with some gusts over northeast Iowa up to 20 kts this afternoon. Decreasing winds will be seen towards and after sunset tonight, remaining south to southeast.